Resonant Cavity Mesa Layout With Integrated ESD Protection
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Solution Overview
Problem
Consumer electronic devices with resonant cavity mesas, such as VCSEL diodes, are susceptible to electrostatic discharge (ESD) damage at varying threshold voltages, particularly at low aperture sizes, leading to potential failure or decreased performance, and existing solutions like separate TVS diode modules are bulky and unsuitable for integration in some applications.
Innovation Solution
An optoelectronic device design that includes a silicon interposer with an array of resonant cavity mesas, where a subset is forward biased as VCSEL diodes or photodetectors and another subset is reverse biased to provide ESD protection, acting as a bidirectional transient voltage suppressor, eliminating the need for a separate TVS diode module by integrating ESD protection within the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate TVS diode modules are used to protect VCSEL diodes from ESD damage, then ESD protection is provided, but the device becomes bulky and integration is difficult
Solution Approach 1:
The patent combines the ESD protection function with the resonant cavity mesas themselves by dividing them into two subsets: one subset operates as VCSEL diodes and another subset operates as TVS diodes. This merging eliminates the need for separate TVS diode modules, reducing device size and simplifying integration while maintaining ESD protection capability.
Solution Approach 2:
The resonant cavity mesas serve dual functions: they act as VCSEL diodes for optical emission/detection and simultaneously provide ESD protection through the TVS diode subset. This multi-functionality allows a single structure to fulfill both operational and protective roles, eliminating the need for additional protective components.
2Area of moving object
If resonant cavity mesas are used with very low aperture size, then device integration is improved, but susceptibility to ESD damage increases
Solution Approach 1:
By merging the ESD protection function into the resonant cavity mesa structure itself through the two-subset configuration, the patent enables low aperture size VCSEL diodes to maintain ESD resistance. The integrated TVS diode subset provides protection without requiring larger aperture sizes.
Solution Approach 2:
The TVS diode subset acts as an intermediary protective element within the resonant cavity mesa array, shielding the low aperture size VCSEL diodes from ESD damage while allowing the VCSELs to maintain their small aperture dimensions for better integration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively protects against ESD damage by utilizing reverse biased mesas to safeguard forward biased mesas during voltage surges, providing a compact and integrated solution that maintains device performance and form factor.
Implementation Method 1
the second subset of resonant cavity mesas may be configured to provide electrostatic discharge (ESD) protection for the first subset of resonant cavity mesas
Implementation Method 2
the second subset of resonant cavity mesas may be reverse biased
Data Source
AI summary
An optoelectronic device includes a silicon interposer and an array of resonant cavity mesas. The array of resonant cavity mesas is monolithically integrated in a set of one or more epitaxial layers and flip-chip bonded to the silicon interposer. The array of resonant cavity mesas includes a first subset of resonant cavity mesas connected to a first subset of conductors of the silicon interposer and biased to a first electrical polarity, and a second subset of resonant cavity mesas connected to a second subset of conductors of the silicon interposer. The second subset of resonant cavity mesas provides electrostatic discharge (ESD) protection for the first subset of resonant cavity mesas.